The present invention relates to an improved truck for shredding and mixing products for zootechnical use.
In the zootechnical field it is known to use combined shredding and mixing trucks with a vertical scroll to prepare animal fodder, particularly for the cattle; these trucks are substantially constituted by a container that is shaped like an inverted frustum and is mounted on a wheeled chassis; a rotating scroll is arranged vertically inside said container, and the profile of its helix lies along an ideal substantially conical surface.
Cutters are fixed to the peripheral region of the scroll and are adapted to shred the product being mixed, which is appropriately loaded from the top and is constituted to a large extent by fibrous material, such as straw and hay added with protein integrators, silage, floury components, etcetera.
With particular reference to FIG. 1 of the accompanying drawings, said figure is a sectional view of the container, designated by the reference letter A, and shows the scroll B and the cutters C that are fixed on its external profile.
In order to contrast the rotary motion of the product being processed that is entrained by the rotating scroll B, countercutters D are arranged vertically in substantially radial positions in the lower part of the container A and can be inserted and extracted through slots provided in the wall of the container A.
Said countercutters D are substantially disk sectors that are pivoted to the container A proximate to their respective vertices.
As shown in FIG. 1, the countercutters D extend upward from the pivoting axis and reach up to a level, considering the bottom of the container A as reference, that affects only the first turn of the helix of the scroll B.
In this manner, when the countercutters are inserted in the container A due to processing requirements, their presence, in addition to the beneficial effect of contrasting the rotation of the material, also has negative effects due to the fact that the scroll, in order to turn said material, must make it rise in level, overcoming the obstacle constituted by said countercutters, and forms a sort of unmixed doughnut in this position.
The vertical motion easily causes the material to overflow from the container A.
Furthermore, the lower parts of the scroll B are stressed more intensely than the upper ones, and the lowermost cutters work more than the upper ones, causing consequent greater wear and non-uniform shredding of the product.
This of course has a negative effect on the wear of the machine parts, on one hand, and on the quality and uniformity of the fodder on the other.
If one tries to solve the problem by reducing the dimensions of the scroll B, the negative effect of moving it away from the countercutters D, reducing their action is obtained.
On the other hand, if the dimensions of the scroll B are increased, the stress to which the motor system is subjected increases, and excessive vertical movements of the material occur, causing it to overflow even more from the container A.
It should also be noted that if large hay bales are inserted, current countercutters D are unable to effectively contrast the rotary motion induced by the scroll B, due to their position, which is adjacent to the bottom of the container A, and therefore the breaking-up and shredding action of said countercutters is very time-consuming in addition to easily causing overflows of material from the upper rim of the container A.
It should also be noted that the above described arrangement of the countercutters D shown in FIG. 1 produces considerable problems in terms of overall machine bulk.
When said countercutters are extracted from the container A, their widest parts in fact protrude considerably in the wall region.
This entails the need to move said countercutter closer to the longitudinal median plane, which is straddled, at the front or at the rear, by the product discharge opening with the corresponding distribution conveyor belt.